The present invention relates in general to a device for aligning sheets which are individually supplied to, and stacked in a collecting tray having a stacking surface and a lateral limiting member extending parallel with the sheet entrance direction as well as an abutment associated with the front end sides of the sheets, such device including a drivable aligning wheel which rests on the incoming sheet and aligns sheets with both the lateral limiting member and the front abutment.
In a device such as disclosed in patent application P 39 41 477.9, a screw wheel is provided by which the sheets when moving under the action of gravity onto a stacking surface of a collecting tray, downwardly inclined in the sheet entrance direction, are aligned with a lateral limiting member and a movable end-side abutment. In the area of the sheet edges to be aligned, a stapling unit is arranged which staples a predetermined number of sheets. The stapled sheet stack is released when the movable abutment is pivoted to its opening position so that the stack can slide out of the collecting tray under the action of gravity and can be fed to a depositing tray. Since the continuously rotating screw wheel rests constantly on the upper surface of the stack, it exerts pressure on the sheet stack in a direction transverse to the release direction so that the stack is moved into an undesired oblique position and cannot be deposited in an orderly manner.
It is known that an axially symmetrical aligning wheel can be used instead of a screw wheel. However, such aligning wheels involve the danger of an incoming sheet impinging linearly and slipping over the aligning wheel so that it cannot be aligned.